[PATCH 8/8] doc: document AT_EMPTY_PATH glitches

---
 doc/glibc-functions/name_to_handle_at.texi | 5 +++++
 doc/glibc-functions/statx.texi             | 4 ++++
 doc/posix-functions/faccessat.texi         | 7 +++++++
 doc/posix-functions/fchmodat.texi          | 9 +++++++++
 doc/posix-functions/fchownat.texi          | 4 ++++
 doc/posix-functions/fstatat.texi           | 4 ++++
 doc/posix-functions/utimensat.texi         | 4 ++++
 doc/posix-headers/fcntl.texi               | 5 +++--
 8 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/doc/glibc-functions/name_to_handle_at.texi b/doc/glibc-functions/name_to_handle_at.texi
index e9cca7d278..e732af2b0e 100644
--- a/doc/glibc-functions/name_to_handle_at.texi
+++ b/doc/glibc-functions/name_to_handle_at.texi
@@ -16,4 +16,9 @@ name_to_handle_at
 This function exists only on Linux and is therefore
 missing on all non-glibc platforms:
 glibc 2.13, macOS 14, FreeBSD 14.0, NetBSD 10.0, OpenBSD 7.9, Minix 3.1.8, AIX 7.1, HP-UX 11.31, Solaris 11.4, Cygwin 2.9, mingw, MSVC 14, Android 9.0.
+
+@item
+When @code{AT_EMPTY_PATH} is used,
+this function does not allow the file name to be a null pointer:
+Linux kernel 6.10.
 @end itemize
diff --git a/doc/glibc-functions/statx.texi b/doc/glibc-functions/statx.texi
index 2544a88b82..d57b488dd2 100644
--- a/doc/glibc-functions/statx.texi
+++ b/doc/glibc-functions/statx.texi
@@ -16,6 +16,10 @@ statx
 This function is missing on many platforms:
 glibc 2.27, macOS 14, FreeBSD 14.0, NetBSD 10.0, OpenBSD 7.9, Minix 3.1.8, AIX 7.1, HP-UX 11.31, Solaris 11.4, Cygwin 2.9, mingw, MSVC 14, Android API level 29.
 @item
+When @code{AT_EMPTY_PATH} is used,
+this function does not allow the file name to be a null pointer:
+Linux kernel 6.10.
+@item
 There is an incompatible function of the same name on some platforms:
 AIX 5.2 or newer.
 @end itemize
diff --git a/doc/posix-functions/faccessat.texi b/doc/posix-functions/faccessat.texi
index 4f32235f9e..3c4a8a951b 100644
--- a/doc/posix-functions/faccessat.texi
+++ b/doc/posix-functions/faccessat.texi
@@ -34,6 +34,13 @@ faccessat
 after a process starts as root and then becomes non-root:
 @c https://sourceware.org/PR18683
 GNU/Linux with glibc 2.32.
+@item
+This function does not support @code{AT_EMPTY_PATH}:
+Linux kernel 2.6.38.
+@item
+When @code{AT_EMPTY_PATH} is used,
+this function does not allow the file name to be a null pointer:
+glibc 2.41, Linux kernel 6.10, Cygwin 3.6, FreeBSD 15.1.
 @end itemize
 
 Other problems of this function:
diff --git a/doc/posix-functions/fchmodat.texi b/doc/posix-functions/fchmodat.texi
index 2b81e807e4..43cde46e2b 100644
--- a/doc/posix-functions/fchmodat.texi
+++ b/doc/posix-functions/fchmodat.texi
@@ -32,6 +32,15 @@ fchmodat
 Some platforms do not allow changing the access bits on symbolic
 links.
 
+@item
+This function does not support @code{AT_EMPTY_PATH}:
+Linux kernel 2.6.38.
+
+@item
+When @code{AT_EMPTY_PATH} is used,
+this function does not allow the file name to be a null pointer:
+Linux kernel 6.10, Cygwin 3.6, FreeBSD 15.1.
+
 @item
 If the @code{AT_SYMLINK_NOFOLLOW} flag is specified,
 this function can fail with @code{errno} set to @code{EMFILE} or @code{ENFILE},
diff --git a/doc/posix-functions/fchownat.texi b/doc/posix-functions/fchownat.texi
index 884bc0a8ba..ca25c42563 100644
--- a/doc/posix-functions/fchownat.texi
+++ b/doc/posix-functions/fchownat.texi
@@ -41,6 +41,10 @@ fchownat
 Portability problems not fixed by Gnulib:
 @itemize
 @item
+When @code{AT_EMPTY_PATH} is used,
+this function does not allow the file name to be a null pointer:
+Linux kernel 6.10, Cygwin 3.6, FreeBSD 15.1.
+@item
 This function sometimes fails with @code{EACCES} when the failure is
 due to lack of appropriate privileges (@code{EPERM}), not to
 search permission denied on the file name prefix (@code{EACCES}):
diff --git a/doc/posix-functions/fstatat.texi b/doc/posix-functions/fstatat.texi
index ee3b075232..1f7ab3124b 100644
--- a/doc/posix-functions/fstatat.texi
+++ b/doc/posix-functions/fstatat.texi
@@ -42,6 +42,10 @@ fstatat
 on some platforms, even when @code{AT_EMPTY_PATH} is not used:
 glibc 2.7, Linux 2.6.38.
 @item
+When @code{AT_EMPTY_PATH} is used,
+this function does not allow the file name to be a null pointer:
+Linux kernel 6.10, Cygwin 3.6, FreeBSD 15.1.
+@item
 This function sets @code{st_ino} only to the low-order 32 bits of
 the inode number of a socket or pipe, which thus can disagree
 with the @code{st_ino} obtained by @code{fstat}:
diff --git a/doc/posix-functions/utimensat.texi b/doc/posix-functions/utimensat.texi
index ccac6c97f4..0441140731 100644
--- a/doc/posix-functions/utimensat.texi
+++ b/doc/posix-functions/utimensat.texi
@@ -51,6 +51,10 @@ utimensat
 this function might not modify the access time as requested:
 Linux kernel 6.9.
 @item
+When @code{AT_EMPTY_PATH} is used,
+this function does not allow the file name to be a null pointer:
+Linux kernel 6.10, Cygwin 3.6, FreeBSD 15.1.
+@item
 This function ignores the flag @code{AT_SYMLINK_NOFOLLOW}:
 Linux kernel 6.8 on a CIFS file system.
 @item
diff --git a/doc/posix-headers/fcntl.texi b/doc/posix-headers/fcntl.texi
index 3eeabfed65..420642f7c0 100644
--- a/doc/posix-headers/fcntl.texi
+++ b/doc/posix-headers/fcntl.texi
@@ -129,8 +129,9 @@ fcntl.h
 Mac OS X 10.3.
 
 @item
-@samp{O_PATH} is not defined on some platforms:
-glibc 2.13, macOS 13, FreeBSD 13.0, NetBSD 9.2, OpenBSD 7.1, Minix 3.3.0, AIX 7.3, HP-UX 11.31, Solaris 11.4, Cygwin 2.9, mingw, MSVC 14.
+@samp{O_PATH} and @samp{AT_EMPTY_PATH} are not defined on some platforms:
+glibc 2.13, macOS 26, FreeBSD 13.0, NetBSD 10.1, OpenBSD 7.9, Minix 3.3.0,
+AIX 7.3, HP-UX 11.31, Solaris 11.4, Cygwin 3.0, mingw, MSVC 14.
 
 @item
 Although POSIX.1-2024 standardized @code{O_CLOFORK},
-- 
2.54.0